Disk and clamp assembly

ABSTRACT

A clamp includes a disk and a clamp engaging the disk, wherein the clamp has protrusions that bite into a surface of the disk. A disk and clamp assembly includes a disk having receiving areas formed therein, and a clamp engaging the disk, where the clamp has protrusions that engage the receiving areas. Another disk and clamp assembly includes a disk having protrusions formed thereon, and a clamp engaging the disk, where the clamp has receiving areas adapted for receiving the protrusions.

FIELD OF THE INVENTION

The present invention relates to disk drive components, and moreparticularly, this invention relates to a disk and clamp assembly.

BACKGROUND OF THE INVENTION

A typical disk drive storage system includes one or more magnetic diskswhich are mounted for co-rotation on a hub or spindle. A typical diskdrive also includes a transducer supported by a hydrodynamic bearingwhich flies above each magnetic disk. The transducer and thehydrodynamic bearing are sometimes collectively referred to as a datahead or a product head. A drive controller is conventionally used forcontrolling the disk drive based on commands received from a hostsystem. The drive controller controls the disk drive to retrieveinformation from the magnetic disks and to store information on themagnetic disks. An electromechanical actuator operates within a negativefeedback, closed-loop servo system to move the data head radially orlinearly over the disk surface for track seek operations and holds thetransducer directly above a desired track or cylinder on the disksurface for track following operations.

Typically the magnetic disks 2 also comprise servo sectors 18 which arerecorded at a regular interval and interleaved with the data sectors 12,as shown in FIG. 1. A servo sector, as shown in FIG. 2, typicallycomprises a preamble 20 and sync mark 22 for synchronizing to the servosector; a servo data field 24 comprising coarse position information,such as a Gray coded track address, used to determine the radiallocation of the head with respect to the plurality of tracks; and aplurality of servo bursts 26 recorded at precise intervals and offsetsfrom the track centerlines which provide fine head position information.When writing or reading data, a servo controller performs a “seek”operation to position the head over a desired track; as the headtraverses radially over the recording surface, the Gray coded trackaddresses in the servo data field 24 provide coarse position informationfor the head with respect to the current and target track. When the headreaches the target track, the servo controller performs a trackingoperation wherein the servo bursts 26 provide fine position informationused to maintain the head over the centerline of the track as thedigital data is being written to or read from the recording surface.

To ensure that the head remains properly aligned with the data tracks,the disks must be securely attached to the spindle. Current practice isto separate the disks in the stack with spacer rings, and position aspacer ring on top of the disk/spacer stack. Then a top ring, called aclamp, with several apertures is placed over the top spacer ring. Thedisks are bolted to the spindle via bolts extending through theapertures in the top clamp. Great pressure must be exerted by the boltson the top clamp in order to prevent slippage of the disks in the eventthat the drive is bumped or uneven thermal expansion that breaks thefrictional coupling, because once the disks slip, the drive loses itsservo and the data is lost.

Disks are typically formed from aluminum or glass. Aluminum is moreeasily deformed, so any external stress can cause deformations to thedisk. Glass, too, will deform under uneven stress patterns.

A major drawback of the current practice is that when the bolts aretightened, the top clamp and spacer become deformed due to the unevenpressures exerted by the individual bolts. The deformation translatesout to the disk, creating an uneven “wavy” disk surface, which is mostprominent at the inner diameter of the disk. Any unevenness (waviness)on the disk surface compounds the tendency to lose the servo, especiallynear the inner diameter zone closest to the spacer ring.

Further, it has been found that stresses induced on the top disk in thestack transfer down and propagate into some or all of the remainingdisks in the stack. Thus, it would be desirable to reduce unevenstresses at the top disk so that the remaining disks remain flat.

Another issue encountered in the prior art is the high cost ofassembling the drives. Each spacer must be placed in the drive and thenthe top clamp added and bolted down. This process is time consuming. Toreduce assembly costs, it would be desirable to couple the top clamp andtop spacer ring together so that they can be placed in the drive at thesame time. This would save a processing step in that only one piece (topclamp-spacer composite) need be handled instead of two parts (top clampand spacer ring individually).

The cost savings obtainable by using a composite structure would beincreased in new high capacity drives which require only a few disks asopposed to several. For example, in a drive with five disks, five partsmust be handled: the top clamp-spacer composite and four more spacerrings. In a drive with only two disks, only two parts are handled: thetop clamp-spacer composite and one spacer.

Additional cost savings would be realized during manufacture of the topclamp and top spacer ring themselves, as it would no longer be necessaryto machine two surfaces in such a way to match flatness.

SUMMARY OF THE INVENTION

A clamp includes a disk and a clamp engaging the disk, wherein the clamphas protrusions that bite into a surface of the disk. A disk and clampassembly includes a disk having receiving areas formed therein, and aclamp engaging the disk, where the clamp has protrusions that engage thereceiving areas. Another disk and clamp assembly includes a disk havingprotrusions formed thereon, and a clamp engaging the disk, where theclamp has receiving areas adapted for receiving the protrusions.

A spacer may also be added to the assembly. The spacer may haveprotrusions adapted to bite into a surface of the disk. The spacer mayalso have protrusions that engage receiving areas of the disk.

The protrusions of the disk, clamp, and/or spacer can be organized in agenerally annular fashion, in a random fashion, etc. The protrusions maybe formed in varying shapes. For example, the protrusions can have atapered points, generally rectangular cross sections, can taper aparttowards free ends thereof, can have bulbous portions towards free endsthereof, and combinations of these.

Preferably, the clamp has a stiffness at least as stiff as a primarymaterial of the disk. In those assemblies with matingprotrusions/receiving areas, an adhesive is positioned in the receivingareas.

Any of these embodiments can be integrated into a magnetic storagesystem.

Other aspects and advantages of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, as well as the preferred mode of use, reference should bemade to the following detailed description read in conjunction with theaccompanying drawings.

FIG. 1 shows a typical format for of a disk surface comprising aplurality of radially spaced, concentric data tracks partitioned into anumber of data sectors and embedded servo sectors for positioning theheads over the disk surfaces while seeking and tracking.

FIG. 2 shows a typical format of an embedded servo sector.

FIG. 3 is a schematic and simplified vertical sectional view of a rigidmagnetic disk drive unit embodying the present invention.

FIG. 4 is a top plan view of the structure shown in FIG. 3.

FIG. 5 is a perspective view of a composite spacer according to oneembodiment.

FIG. 6A is an exaggerated cross-sectional view of a composite ring withupper and lower layers coupled together via a series of ridges andtroughs.

FIG. 6B is an exaggerated cross-sectional view of a composite ring withupper and lower layers coupled together via a series of dovetailprotrusions and receiving areas.

FIG. 6C is an exaggerated cross-sectional view of a composite ring withupper and lower layers coupled together via a series of bulbousprotrusions and receiving areas.

FIG. 7 is a side view of the first layer of FIG. 6A taken along lines7-7 of FIG. 6A.

FIG. 8 is a cross-sectional view of a clamp/spacer ring assemblyaccording to one embodiment.

FIG. 9 is a cross-sectional view of a clamp/spacer ring assemblyaccording to another embodiment.

FIG. 10 is a cross-sectional view of a clamp/spacer ring assemblyaccording to yet another embodiment.

FIG. 11 is a cross-sectional view of a clamp with teeth (or otherprotrusions) that bite into the surface of a disk.

FIG. 12 is a cross-sectional view depicting addition of a spacer to theclamp and disk assembly of FIG. 11.

BEST MODE FOR CARRYING OUT THE INVENTION

The following description is the best embodiment presently contemplatedfor carrying out the present invention. This description is made for thepurpose of illustrating the general principles of the present inventionand is not meant to limit the inventive concepts claimed herein.

Referring now to the drawings wherein like reference numerals designatelike or similar parts throughout the several views there is illustratedin FIG. 3 a cross-sectional diagram of parts of a data storage diskdrive system 30 including a rigid magnetic disk drive unit generallydesignated as 32 and a control unit generally designated as 34. While amagnetic disk drive unit is illustrated, it should be understood thatother mechanically moving memory configurations may be used. Unit 32 isillustrated in simplified form sufficient for an understanding of thepresent invention because the utility of the present invention is notlimited to the details of a particular drive unit construction. Afterdata storage disk drive system 30 is completely assembled, servoinformation used to write and read data is written using the disk drivesystem 30.

Referring now to FIGS. 3 and 4 of the drawing, disk drive unit 32includes a stack 36 of disks 38 having at least one magnetic surface 40.The disks 38 are mounted in parallel for simultaneous rotation on and byan integrated spindle and motor assembly 46. The disks 38 are separatedby spacers 33 and are coupled to the spindle at the top by a compositeclamp ring 70 which is pressed onto the stack of disks 38 by bolts 35.

Data information on each disk 38 are read and/or written to by acorresponding transducer head 48 movable across the disk surface 40. Ina disk drive using a dedicated or hybrid servo, one of the disk surfaces40′ stores servo information used to locate information and data on theother disk surfaces 40.

Transducer heads 48 are mounted on flexure springs 50 carried by arms 52ganged together for simultaneous pivotal movement about a supportspindle 54. One of the arms 52 includes an extension 56 driven in apivotal motion by a head drive motor 58. Although several drivearrangements are commonly used, the motor 58 can include a voice coilmotor 60 cooperating with a magnet and core assembly (not seen)operatively controlled for moving the transducer heads 48 in synchronismin a radial direction in order to position the heads in registrationwith data information tracks or data cylinders 62 to be followed andaccess particular data sectors 64. Although a rotary actuator is shown,it should be understood that a disk drive with a linear actuator can beused. Data storage disk drive system 30 is a modular unit including ahousing 66. The various components of the disk drive system 30 arecontrolled in operation by signals generated by control unit 34 such asmotor control signals on line 46A and position control signals on line58A.

Numerous data information tracks 62 are arrayed in a concentric patternin the magnetic medium of each disk surface 40 of data disks 38. A datacylinder includes a set of corresponding data information tracks 62 forthe data surfaces 40 in the data storage disk drive system 30. Datainformation tracks 62 include a plurality of segments or data sectors 64each for containing a predefined size of individual groups of datarecords which are saved for later retrieval and updates. The datainformation tracks 62 are disposed at predetermined positions relativeto servo information, such as a servo reference index. In FIG. 4 onesector 64 is illustrated as SECTOR 0 with a fixed index or mark INDEXfor properly locating the first data sector. The location of each nextsector 64 is identified by a sector identification (SID) pulse read bytransducer heads 48 from surfaces 40, 40′.

FIG. 5 illustrates a composite top clamp ring 70 according to oneembodiment. The composite ring 70 includes a stiff annular upper layer72 that provides rigidity to the clamping structure 70 by providing amore even distribution of stresses on the disks below from the clampingbolts coupled to the composite ring 70 through the apertures 76, whichin turn reduces deformation of the disk(s). An annular lower layer 74 isfixedly coupled to the upper layer 72. The lower layer 74 may be ofsecondary stiffness and is preferably made of a material similar to thedisk, e.g., aluminum or ceramic. The highly rigid upper layer 72 of thecomposite ring 70 reduces deformation caused by the clamping stresses,yet the composite ring 70 provides high mechanical stability due tointegral material matching for the clamping interface. Thematerial-matching at the ring-disk interface allows the lower layer 74and the disk to expand and contract together under temperaturevariations. (Using a hard material for the lower layer 74 would causethe bottom layer to expand out of phase with the disk.)

The upper layer 72 of the composite ring is preferably made of amaterial with a high hardness and high modulus so that it is lesssusceptible to bending and/or cracking under the stress of the clampingforces. Preferably, the upper layer 72 has a material hardness and/ormodulus that is at least as hard as the disk itself. Thus, if analuminum disk is used in the drive, the stiffening layer should have ahardness at least about the same as the aluminum material used to formthe disk. Illustrative materials from which the upper layer 72 can beformed are nickel, titanium, chrome, stainless steel, materials treated(e.g., doped) for stiffness and hardness, silicon nitride, aluminumnitride, alloys, composites, etc.

The lower layer 74 is preferably constructed of a material which is of asimilar or about the same coefficient of thermal expansion as that ofthe primary material of the disk, i.e., disk substrate of glass,aluminum, etc. The thermal conductivity parameter shown in Table 1(below) is important but to a lesser extent than the coefficient ofthermal expansion and the Young's modulus of the material. The thermalconductivity should be similar to the disk since heat from the motordoes not build up in the lower layer 74 but can transmit to the diskuniformly.

The following table lists several materials from which the compositering 70 can be constructed, and their properties. Note that the modulusis a measure of the load a material can handle before it starts todeform.

TABLE 1 Coefficient of Thermal Thermal Hardness Modulus ConductivityExpansion Material (kg/mm²) (GPa) (W/m-K) (10⁻⁶/C.) Aluminum 27 70 22125 Chrome 125 26 14 6 Titanium 65 110 2 8.5 Nickel 210 200 60 13 Glass185 63 1 4 Stainless Steel 160 205 16 12

An illustrative range of materials usable in the composite ring 70 havea hardness of about 20 to about 250 kg/mm², a modulus of about 60 toabout 300 GPa and a thermal expansion between 1 and 25 (10⁻⁶/C). Notethat glass and aluminum have a similar Young's modulus, but the aluminumhas about 6 times the coefficient of thermal expansion as glass.Therefore, an aluminum spacer is preferred for use with aluminum disks,while a ceramic spacer is preferred for use with glass disks.

The following table illustrates exemplary Young's modulus ratios for theupper and lower layers of the composite ring 70. The modulus ratio isimportant as a measure of how well the composite ring 70 will providethe desired properties.

TABLE 2 Modulus Ratio of Two Materials: Material Combination first +second layer Stainless Steel Clamp with Aluminum spacer 205/70 = 3.0Stainless Steel Clamp with Glass spacer 205/63 = 3.3 Titanium Clamp withAluminum spacer 110/70 = 1.6 Titanium Clamp with Glass spacer 110/63 =1.8

A preferred modulus ratio range can be shown by the following:1.0<Modulus Ratio<5.0. However, this range may not be all inclusive andwould allow some combinations outside of this range, especially usingnonmetallic disks and clamps, i.e. plastic and silicon disks withplastic and silicon lower layers 74. When glass disks are used, anillustrative modulus ratio of about 3.3 is provided by a stainless steelupper layer 72 and a ceramic lower layer.

A middle layer of the composite ring, positioned between the upper andlower layers 72, 74, can be added to achieve the desired overall modulusratio. The middle layer can be constructed of another material such asone or more of stainless steel, chrome, nickel, etc. and composites andalloys thereof.

The layers of the composite ring 70 can be coupled together using anysuitable process. Several techniques to perform such bonding aredescribed below. Three particular techniques include mechanical bonding,adhesive chemical bonding, and bonding at the molecular level.

Mechanical bonding of the layers can be achieved by protrusions andcorresponding receiving areas such as ridges/textured lines andcoincident troughs. The mechanical coupling encourages the variouslayers to expand and contract together, thereby maintaining the properalignment.

FIG. 6A is an exaggerated view of the composite ring 70 with the upperand lower layers 72, 74 coupled together via a series of ridges 82 andtroughs 84. FIG. 7 shows the ridge structure on the bottom of the upperlayer 72 which mates with a trough structure on the lower layer 74 tocreate the composite ring. The ridges 82 mate into the troughs 84,providing mechanical bonding and strength between the layers. With thistype of mating for the composite ring 70, high structural integrity andsuperior bonding is maintained for a system that is exposed to the highstress of clamping a multi-disk pack.

Other variations to create the mechanical coupling can include random ornonrandom fingerlike perturbations and recesses, teeth (see FIG. 9),etc. To enhance the coupling, “dovetail” protrusions, bulbousprotrusions, etc. can be used to form semi-permanent or permanentcoupling. Note FIGS. 6B and 6C.

Chemical bonding can also be used individually, or in combination withprotrusions/receiving portions as described in the immediately precedingparagraphs. Adhesives such as silicon-based adhesives can be used tocreate the chemical bond. In a similar manner, bonding at the molecularlevel can be achieved by sintering, welding, ultrasonic welding, etc.

Because the two layers 72, 74 are coupled together, a processing stepduring drive assembly is saved in that only one piece (clamp-spacercomposite) need be handled instead of two parts (clamp and spacer).Additional cost savings are realized during manufacture of the annularlayers 72, 74 themselves, as it is longer necessary to machine twosurfaces to obtain a hardness match.

A clamp/spacer ring assembly according to another embodiment isconstructed at least in part of plastic. Such a ring assembly 90,particularly suitable for use in a drive having disks themselvesconstructed at least in part of a plastic material, is shown in FIG. 8.The ring assembly 90 according to one embodiment includes a stiffannular clamp 92, followed by an annular plastic spacer ring 94. Theclamp 92 is preferably constructed of materials described above withrespect to the first layer of the composite ring. The spacer ring 94 ispreferably constructed of any plastic material having properties similarto that of the plastic in the disks, and may be formed or molded as asingle layer, a composite structure, etc. Illustrative plastic materialsinclude polyolefins, polyethylenes, polycarbonates, polystyrenes,polyvinyl chlorides, polymers, resins, etc. In the embodiment shown inFIG. 8, the spacer ring 94 has glass beads 96 (or other materialstrengthening elements) of any shape embedded into the plastic matrix ina non-uniform manner. Preferably, the material strengthening elementsare harder than the material from which the spacer ring 94 isconstructed. This allows a gradient of density from high to low (highclosest to the clamp 92) which will allow a gradient of thermalexpansion to be made more uniform from the stiff clamp 92 to the lowerportion of the plastic spacer ring 94. Without this gradient the clamp92/spacer ring 94 combination would suffer from thermal expansionproperties as well as modulus problems. The plastic lower layer closestto the clamp 92 would have a high density of materials, allowing for athermal expansion and modulus closest to the clamp 92. The portion ofthe plastic ring closest to the plastic disk would then have materialproperties very similar to that of the plastic disk being clamped.Preferably, some type of mechanical mating (e.g., see FIGS. 9 and 10) isimplemented to integrally couple the layers to prevent slipping of thelayers, particularly where dissimilar materials are used.

Another way to obtain a non-uniform plastic structure is with teeth 102,as shown in FIG. 9. The teeth 102 are preferably extensions from theclamp 92 which extend into the plastic matrix. The teeth 102 may beannularly aligned, segmented, randomly placed, etc. This will increasethe density and modulus of the plastic structure and will give itsimilar material properties as explained in the previous paragraph. Notealso that the teeth 102 and ridges 104 may also extend from the plasticring 94 into the clamp 92.

Yet another way to obtain a non-uniform plastic structure is with aridge/trough 104, 106 combination, as shown in FIG. 10. The teeth 104are preferably extensions from the clamp 92 which extend into theplastic matrix. The ridges 104 may be annularly aligned, segmented,randomly placed, etc. This will increase the density and modulus of theplastic structure and will give it similar material properties asexplained in the previous paragraphs. Note also that the ridges 104 mayalso extend from the plastic ring into the clamp 92.

The clamp 92 and plastic spacer ring 94 of the ring assemblies shown inFIGS. 8-10 can be installed individually in the disk drive. Themechanical coupling causes the layers to expand and contract together ina uniform fashion, thereby preventing the disk from going off-center.Alternatively, the clamp 92 and plastic spacer ring 94 can be fixedlycoupled together to form a composite structure similar to that describedabove with respect to FIG. 5.

Thus, the composite structure described herein will reduce the partscount and the cost associated with an individual clamp 92 and spacerring 94. The composite material choices will also allow better thermalexpansion, stiffness and modulus which is mated and matched perfectly tothe top disk of the stack. Under torquing requirements the stress isspread out evenly over the top disk so as to minimize tangential andradial curvature effects.

Composite structures that have a blend of coupling morphologies are alsoto be considered as a composite structure that are mechanically bondedto one another. The set of mechanical couplings indicated in theindividual FIGS. 6A, 6B and 6C can be blended into one as a combination,i.e. A+B, A+C, B+C. Also, for the plastic clamp/ring structure shown inFIGS. 9 and 10, these can also be combined, i.e. 9+10.

Another embodiment of the present invention includes clamps and spacerswhere the clamps and spacers are clamped directly to the disk. Theembodiments described below result in reduced potato chipping as theforce exerted by the clamp and spacer(s) on the disk is distributed moreevenly across the disk surface. A further advantage is that thepotential of slippage of the disk with respect to a clamp and spacer isdramatically reduced so as to be substantially nonexistent, due to themating engagement. One skilled in the art will also understand that theteachings of the clamp and spacer combinations described above can beadapted to create variations on the embodiments described below.

In one embodiment, the clamps and/or spacers “bite” into the disksurface. By biting into the disk surface, what is meant is thatprotrusions extending from the clamp and/or spacer engages and deformsthe surface of the disk. If the disk is plastic or metal, the disk canbe heated to aid in deformation.

FIG. 11 illustrates an embodiment in which a clamp 122 has teeth 124 (orother protrusions) that bite into the surface of a disk 126. In thisembodiment, the clamp is formed of a hard material, i.e., harder thanthe portion of the disk to which the clamp engages the disk. Forexample, the clamp can be formed of metal while the portion of the diskengaging the clamp can be plastic that deforms upon bolting the clamp tothe disk. This configuration provides the advantage that a single boltcan be inserted through a central opening of the clamp and disk to affixthe clamp and disk to the motor, thereby further reducing the time andcost of manufacture. Prior art configurations use large bore screws toprovide adequate force to prevent disk slippage. Here, the teeth willprevent slippage by mechanical bonding. However, the conventionalconfiguration of multiple bolts/screws can also be used to attach theclamp and disk to the motor.

FIG. 12 depicts the embodiment of FIG. 11, with a spacer 128 separatingthe upper disk from a lower disk. In the structure shown, the spacer hasteeth on both sides thereof. The teeth of the spacer engage the disks,forming mechanical couplings therewith in a manner similar to the waythe clamp couples to the upper disk.

In a variation, the clamp and/or spacer may have recessed regions, suchas dimples or channels, in the disk-engaging surface thereof that allowthe surface of the disk to deform into the recessed regions uponcompression. If the disk is plastic or metal, the disk can be heated toaid in deformation.

In another embodiment, the clamp and/or spacer engages protrusionsand/or receiving areas (e.g., teeth, nubs, etc. and complementarygrooves, channels, dimples, holes, etc.) pre-formed on the disk. Thus,the clamp and spacer can have protrusions, recesses, or both. Likewise,the disk can have complementary protrusions, recesses, or both. Forexample, the disk can be formed with recesses that receive protrusionsfrom the clamp and/or spacer in a similar manner as the spacer/clampassemblies described in FIGS. 6A-C, 9 and 10 and related discussion. Ifthe disk is plastic, recesses can be molded in the disk. If the disk isalumina, recesses can be machined into the disk. If the disk is glass,recesses in the disk can be formed by etching.

In any of these embodiments, the clamp and/or spacer can be amulti-layer (composite) structure having a soft engaging layer thatreceives protrusions extending from the disk. In such an embodiment, atleast one layer of the clamp would be stiff to resist deformation uponattachment to the spindle. The spacer may or may not include a stifflayer.

To enhance the mechanical coupling of the clamp/spacer to the disk, anadhesive can be added.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. A clamp for coupling a disk to a spindle, comprising: a clamp forengaging a magnetic disk, wherein the clamp has non-randomly formedprotrusions that bite into a surface of the disk at least beyond anoverall plane of the surface being bitten into, the protrusions having asubstantially similar shape when engaging the disk and when not engagingthe disk, wherein the protrusions have a shape characterized by at leastone of tapering apart towards free ends thereof, tapering to a point,and having a generally rectangular cross section.
 2. A clamp as recitedin claim 1, wherein the protrusions are organized in a generally annularfashion.
 3. A clamp as recited in claim 1, wherein the protrusions havea greater stiffness than a primary material of the disk into which theprotrusions bite.
 4. A clamp as recited in claim 3, wherein theprotrusions deform the surface of the disk being bitten into.
 5. A clampas recited in claim 1, wherein the clamp has a stiffness at least asstiff as a primary material of the disk.
 6. A clamp as recited in claim1, wherein the clamp is a composite structure comprising at least twolayers, each of differing materials.
 7. A clamp as recited in claim 1,further comprising a spacer, wherein the spacer has protrusions adaptedto bite into a surface of the disk.
 8. A magnetic storage system,comprising: the disk and clamp assembly of claim 1; at least one headfor reading from and writing to the disk, each head having: a sensor; awrite element coupled to the sensor; a slider for supporting the head;and a control unit coupled to the head for controlling operation of thehead.
 9. A clamp, comprising: a clamp for engaging a magnetic disk,wherein the clamp has non-randomly formed protrusions that bite into asurface of the disk at least beyond an overall plane of the surfacebeing bitten into, the protrusions having a substantially similar shapewhen engaging the disk and when not engaging the disk wherein theprotrusions have bulbous portions towards free ends thereof.
 10. A diskand clamp assembly, comprising: a magnetic disk having receiving areaspre-formed therein, wherein the receiving areas do not extend throughthe magnetic disk; and a clamp engaging the disk, wherein the clamp haspre-formed protrusions that engage the receiving areas, the protrusionshaving a shape that is complementary to the receiving areas, wherein theclamp is a composite structure comprising at least two layers, each ofdiffering materials, wherein the layer of the clamp engaging the diskhas about a same stiffness as a primary material of the disk, whereinanother of the layers has a stiffness harder than the layer of the clampengaging the disk.
 11. An assembly as recited in claim 10, wherein theprotrusions are organized in a generally annular fashion.
 12. Anassembly as recited in claim 10, wherein the protrusions taper to apoint.
 13. An assembly as recited in claim 10, wherein the protrusionshave a generally rectangular cross section.
 14. An assembly as recitedin claim 10, wherein the protrusions taper apart towards free endsthereof.
 15. An assembly as recited in claim 10, wherein an adhesive ispositioned in the receiving areas.
 16. An assembly as recited in claim10, wherein the clamp has a stiffness at least as stiff as a primarymaterial of the disk.
 17. An assembly as recited in claim 10, whereinthe protrusions have bulbous portions towards free ends thereof.
 18. Anassembly as recited in claim 10, further comprising a spacer, whereinthe spacer has protrusions that engage receiving areas of the disk. 19.A magnetic storage system, comprising: the disk and clamp assembly ofclaim 10; at least one head for reading from and writing to the disk,each head having: a sensor; a write element coupled to the sensor; aslider for supporting the head; and a control unit coupled to the headfor controlling operation of the head.
 20. An assembly, comprising: amagnetic disk having receiving areas pre-formed therein, wherein thereceiving areas do not extend through the magnetic disk; and a clampengaging the disk, wherein the clamp has pre-formed protrusions thatengage the receiving areas, the protrusions having a shape that iscomplementary to the receiving areas, wherein the protrusions havebulbous portions towards free ends thereof.
 21. A disk and clampassembly, comprising: a magnetic disk; and a clamp engaging the disk,wherein the clamp has non-randomly formed protrusions that bite into asurface of the disk at least beyond an overall plane of the surfacebeing bitten into, the protrusions having a substantially similar shapewhen engaging the disk and when not engaging the disk, wherein theprotrusions have a shape characterized by at least one of tapering aparttowards free ends thereof, tapering to a point, and having a generallyrectangular cross section.